A fitting system of this type is known from DE 20 2010 015 171 U1. Actuation of the hand lever causes rotation of the transmission rod which, in turn, unlocks the two fittings counter to the force of the spring arrangements contained therein. The torque characteristic of the spring arrangements serving to secure the locked state runs linearly, i.e. the torque opposed to the unlocking operation rises sharply during the unlocking operation as the angle of rotation increases. In order to increase the ease of operation, a flatter profile would be advantageous. For example, it is proposed in DE 196 33 782 C1 to use a helical buckling spring for securing the locked state of the fitting system. The characteristic of said spring runs virtually independently of the unlocking path, and therefore the force which is opposed to the unlocking operation and is to be overcome by the user remains virtually constant.
In the case of a fitting system described in DE 10 2011 106 285 A1, what are referred to as shaped springs which are arranged symmetrically around the component rotating during the unlocking are used. Said shaped springs are in contact with a component rotating during the unlocking and the shape of said shaped springs and the shape of the surface of the moving part in sum produce a latching effect or a non-linear profile of the torque over the angle of rotation. The comparatively large distances of the contact between shaped springs and moving component lead here to relatively high frictional work and to a corresponding hysteresis of the entire unlocking and locking process.